Advanced Automotive Gasoline Engines HIGHLIGHTS

PROCESS AND TECHNOLOGY STATUS – Internal combustion engine technology is constantly evolving. A number of improvements in gasoline-powered vehicles have been made to optimize combustion, improve fuel economy and reduce emissions. Examples of advanced gasoline technologies include reduced engine friction losses, direct gasoline injection, engine downsizing with turbocharger, variable valve actuation (VVA) and homogeneous charge compression ignition (HCCI). The majority of these technologies are already commercially available or close to being on the market. Although HCCI technology is still under development for both gasoline and diesel engines, it promises improvement in fuel economy and exceptionally low NOx and soot emissions.

PERFORMANCE AND COSTS – A study by the US Environmental Protection Agency (EPA, 2008) presents the potential CO2 reduction and incremental compliance costs for a number of advanced gasoline technologies as compared to conventional port-fuelled injection vehicles. The costs account for both direct manufacturing costs and indirect costs. The technologies covered - and related CO2 reduction and incremental compliance costs in 2006 US dollars – include a) engine friction reduction (1-3%, $0-126); b) homogeneous direct injection (1-2% $122-525); c) stratified direct injection (9-14%, $872-1275); d) downsizing with turbocharging (6-9%, $120-690); e) variable valve timing (1-4%, $59-209); f) variable valve control (3-6%, $169-1262); and g) cylinder deactivation (6%, $203).

POTENTIAL AND BARRIERS – Car ownership is expected to grow in many OECD countries as well as in emerging economies. Demanding environmental concerns and fuel economy standards, as well as increasing fuel prices, are the major drivers for advancement in engine technologies. The IEA study Energy Technology Perspectives (IEA, 2008) suggests that improving the fuel economy of light-duty vehicles (car, small van and sport utility vehicles) would be one of the most important and cost-effective measures to help reduce CO2 emissions in the transport sector. Given the maturity of some advanced gasoline technologies, and the near-term and cost-effective solutions they can offer to energy and emissions concerns, there is neither technical-economic nor infrastructure barrier for deployment, although some technical bottlenecks have to be solved for technologies such as the HCCI. ______

TECHNOLOGY STATUS AND PERFORMANCE - Advanced gasoline technologies include a variety of Table 1 – Advanced Technologies for Gasoline Engines new components and systems aimed at optimizing combustion and thereby improving the fuel economy Technology Status and reducing the emissions of greenhouse gases and Reduced Engine Friction Losses Production other pollutants. Major innovations are listed in Table 1. Direct Gasoline Injection (incl. Production Reduced engine friction technologies include homogeneous/ stratified charge) systems, components and materials that minimize the Downsizing with Turbocharging Production friction between moving metal parts in the engine. Variable Valve Actuation Production These technologies are available in a significant Cylinder Deactivation Production number of engine designs [1]. Several friction reduction Variable Compression Ratio Prototype opportunities have been identified in piston surfaces Homogeneous charge compression ignition Prototype and rings, crankshaft design, improved material (HCCI) coatings and roller cam followers. Various studies

suggest that the CO2 reduction potential for engine friction reduction technologies may range from 1-5% (stoichiometric) DI engines, a high-pressure fuel [1,2,3]. injector sprays fuel directly into the combustion In the gasoline direct injection (DI) engines, fuel is chamber early enough in the cycle to promote injected at high pressure directly into the combustion homogeneous fuel-air mixing. These engines have the chamber rather than into air intake manifolds. The key potential to reduce hydrocarbon emissions, increase advantage is the improvement in fuel efficiency. The power and improve fuel economy, while taking technology was developed more than 10 years ago and advantage of the highly-effective catalytic after- a number of different manufacturers are now using treatment systems, the same as the port fuel injection these types of engines in commercially available (PFI) engines. Various studies suggest a CO2 emission vehicles. The use of sulphur-free fuels is necessary to reduction potential ranging from 1-5% [1,3,4] in obtain the maximum benefit from this technology. comparison with PFI and multi-point injection. These engines are often supplemented with turbo-charging, Depending on the ignition and combustion mode and on 1 2 the formation process of the mixture, DI engines can be supercharging , or both . They are available from categorized in homogeneous charge, and stratified charge, spark ignition. In the homogeneous charge 1 Turbochargers and superchargers are air compressors that allow more air into an engine; turbochargers are powered by exhaust gases, while superchargers run directly on engine power. 1

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several automobile companies worldwide, and more valve. The advantages of using VVT include deployment is expected in the near future. Stratified improvement in full-load volumetric efficiency which charge DI engines involve concentrating fuel spraying results in increased torque and reduction in pumping close to the spark plug rather than throughout the whole losses during low-load operation, which results in of the combustion chamber. The aim is to produce an reduced fuel consumption. Depending on the design, overall lean stratified mixture. These engines operate EPA (2008) estimates that VVT may enable 1-4% in at least two modes, depending on load and speed. reduction in CO2 emissions compared to fixed-valve During low-load and low-speed operation, the engine engines. The VVL system controls the lift height of the runs with a stratified charge and with lean mixtures. At valves using two different approaches: discrete VVL high-load and high-speed operation, the engine and continuous VVL. Compared to VVT, VVL offers a operates as a stoichiometric homogeneous charge DI further reduction in pumping losses and low-load fuel engine. These engines offer higher CO2 reduction consumption. There may also be a small reduction in potential than homogenous charge DI engines, ranging valve train friction when operating at low valve lift. Most from 8-14% compared to PFI and multi-point injection of the fuel economy gain is achieved with VVL on the [1, 2 , 3, 4], However, major impediments are cost, inlet valves only. This is considered to be a cost- complexity and the requirement of expensive lean NOx effective technology when applied in addition to VVT traps in the exhaust after-treatment system. Stratified (cam phase control) [1]. A number of manufacturers charge DI engines are currently in production (wall- have implemented VVL (or VVT with VVL) into their guided variant), but there is a shift towards the spray- fleet [10, 11, 12]. Based on standard (ECE) driving guided injection variants [1, 4, 5] as they improve cycles, automotive brochures suggest that the VVL injection precision and targeting towards the spark plug, system provides fuel savings of up to 10%, and thus increasing lean combustion stability. These improves cold start behaviour [10]. Various studies systems offer improved fuel economy and reduced confirm CO2 reductions of 3-7%. emissions. Stratified charge spray-guided DI engines 3 Cylinder deactivation allows an engine to run on are nearing production . The availability of low-sulphur part (usually half) of its cylinders during light-load fuels and improved lean catalyst technology will speed operation. For example, a 6-cylinder (V6) engine will the process up. run on all cylinders during acceleration (or under high Engine downsizing is seen as one of the most load), and switch to four or three cylinders for cruising important technologies to reduce fuel consumption and or low-speed drive. This technology is aimed at large CO2 emissions through improved engine efficiency, capacity engines (V6, V8 and V12 engines). Pumping lower weight and lower frictional losses [6,7]. It involves losses are significantly reduced when the engine is a substitution of a naturally-aspirated engine by an operated in the “part-cylinder” mode. Several engine of smaller swept volume. The downsized engine manufacturers have recently incorporated this is typically turbocharged to maintain adequate levels of application into their models. EPA (2008) and IEA torque and power output. The amount by which the (2005) suggest that CO2 reductions associated to these engines are downsized vary depending on the amount systems range from 6-8%. of boost provided by the turbocharger and/or Variable Compression Ratio (VCR) technology supercharger. For example, automotive brochures enables the compression ratio of an engine to be show that a 1.4 litre engine with the application of both automatically adjusted to optimise the efficiency of the turbo and supercharging provides an average fuel combustion process under different load and speed economy of 13.9 km/l in the combined cycle and conditions. The compression ratio controls the amount produces torque (240 Nm) equivalent to a 2.5 litre by which the fuel/air mixture is compressed in the standard gasoline engine (which has an average fuel cylinder before it is ignited. This is one of the most economy of 10 km/l) [8, 24]. Another automotive important factors that determines how efficiently the brochure suggests that a 2.5-litre gasoline engine with the engine can utilize the fuel energy. At low speed, a VCR power of 123 kW and torque of 211 Nm can be replaced engine operates with high compression ratio in order to by a 2-litre turbo engine, with a 9% reduction in fuel maximize fuel efficiency, whilst at high speed, low consumption [9]. Depending on the amount of downsizing, compression ratios are used. The potential benefits and various studies suggest a 2-12% CO reduction. 2 the importance of VCR technology have long been Variable Valve Actuation (VVA) involves controlling known, but it is not commercially available yet due to its the lift, duration and timing of the intake (or exhaust) mechanical complexity. Research done by the valves for air flow. There are two main variants: European Commission Community showed that VCR variable valve timing (VVT) and variable valve lift engines can achieve a reduction of fuel consumption of systems (VVL). The VVT has now become a widely up to 9%, compared to state-of-the-art turbocharged adopted technology. Manufacturers are using many gasoline engines with a constant compression ratio of different types of VVT mechanisms (or cam phaser 8.9 [13]. It also suggests that an additional fuel savings systems) to control timing of the intake and exhaust of up to 18% can be obtained by downsizing the engine by 40%, while keeping torque and performance constant through high boosting. Thus, this technology 2 US EPA (2008) suggests that a turbo and downsized could enable an overall fuel consumption reduction of stoichiometric GDI offers CO2 reductions of 5-7% relative to stoichiometric GDI without boosting. up to 27%. 3 According to Drake and Haworth (2007), SG-SIDI engines with piezoelectric pintle injectors are nearing projection. 2

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Gasoline Homogeneous Charge Compression supplier. To these costs, an indirect cost mark-up (HCCI) - also known as Controlled Auto-ignition (CAI) - factor of 50% is to be added to generate the compliance is an alternative engine-operating mode that does not costs that are then compared to a baseline vehicle. The rely on the spark events to initiate the combustion. In technologies covered in this study (priced in dollars and the HCCI engine, fuel and air are premixed to form a converted to euros6) include engine friction reduction homogeneous mixture; on compression, combustion (€0-88), VVT (€41-146, depending on mechanisms occurs by self-ignition at multiple sites [1, 5, 9]. HCCI used), VVL (€118-883, depending on mechanisms operates in a very lean fuel-air mixture or with a mixture used), cylinder deactivation (€142, for a large car only), that is considerably diluted with exhaust gases either Homogeneous DI (referred to as GDI-stoichiometric in re-injected (EGR) or kept in chamber (to increase the the study, €85-368), stratified DI (referred to as GDI- charge temperature as well as to control excessive lean burn in the study, €525 relative GDI-stoich), and rates of heat release) [1, 4, 14]. A major advantage of downsizing with turbocharging (€84-483). This EPA HCCI is the exceptional low level of NOx emissions due study also suggests learning impact to enable lower to the lower peak-temperature inside the combustion per-unit cost of production as soon as manufacturers chamber. High CO and unburned hydrocarbons gain experience in production and improve in areas emissions can be the result of incomplete reaction in such as simplifying machining and assembly cool wall boundary layers, but conventional three-way operations. The “learning rate” is expressed as a catalysts are most efficient for removal. Soot emissions percentage reduction in costs for each doubling of are also very low or negligible due to the homogeneous production. The EPA suggests a 20% learning rate for nature of the premixed charge. In terms of fuel all newly applied technologies. The joint economy, the technology can lead to a 10% TNO/IEEP/LAT study (2006) presents cost data in the improvement for a simulated European drive cycle, form of additional manufacturers’ costs compared to compared to a homogeneous DI gasoline engine [6]. 2002 baseline gasoline vehicles (small, medium to The major challenges of HCCI are the control of ignition large, with 4/6 cylinder in-line and multipoint injection). timing and the operation over a wide range of engine The study provides technology costs and cost ranges speed and loads [4]. Unlike diesel engines where auto- for small and large cars, namely, engine friction ignition and combustion phasing can be controlled by reduction (€40-60); DI-homogeneous charge (€125- injection timing, HCCI is controlled primarily by in- 175); DI-stratified charge with lean burn (€320-480); cylinder temperature and temperature distribution. This medium (20%) and strong (≥ 30%) downsizing with requires variable exhaust gases re-injection (EGR) turbocharging (€225-510); and VVT (€100-200). rates, as well as sophisticated variable-valve actuation The IEA Energy Technology Perspective (2008) and control systems. Because HCCI engines operate suggests an incremental cost for both engine (incl. VVT, in a limited speed/load range, commercial applications turbocharging and direct injection) and non-engine are likely to operate in a “dual-mode” between HCCI technologies (not discussed in this paper) ranging from and Spark Ignition (SI) application [1]4. This dual-mode €1960 to €2380 [16]. In 2008, EUCAR, CONCAWE strategy has recently been demonstrated by a car and JRC presented their price assumptions for key manufacturer on two concept vehicles based on components, systems and technologies used in their conventional, production-based models [15, 23]5. HCCI economical assessment of the Tank-To-Wheel (TTW) implementation is thought to be about 5-10 years away study. The prices provided for these components are from high-volume production. equivalent to delivered costs to vehicle manufacturers and no mark up to include further costs (e.g. warranty) CURRENT COSTS AND COST PROJECTIONS - is included. The study assumes a volume of more than Several studies provide costs of the various advanced 50,000 units per year, projected for beyond 2010. The gasoline technologies. The costs vary depending on components (and their price assumptions) covered in the definition of cost and method and assumptions this study include friction improvement (€60), used. A summary of the cost data can be found in gasoline/spark-ignition direct injection (€500), Tables 2-4. The US EPA study in 2008 presented turbocharging (€180), and 20% downsizing for incremental compliance costs for each technology, gasoline/spark-ignition (€220) [21, 22]. which account for both the direct manufacturing costs and the indirect costs. Firstly, the piece costs for an POTENTIAL AND BARRIERS - Major drivers for the individual piece of hardware or system (e.g. an intake development and the introduction of new engine cam phaser to provide VVT) are estimated, which is the technologies include the need to meet environmental price paid by the manufacturer to a Tier 1 component goals (e.g. Kyoto Protocol) and legislations. There are several fuel economy and greenhouse gas (GHG) emissions standards for passenger cars currently being 4 proposed, already established or in the process of Spark Ignition (SI) application would be used at higher loads, at idle or when engine is started cold. revision around the world. The fuel economy standards 5 These HCCI prototypes were built on the integration of other include the US Corporate Average Fuel Economy advanced engine technologies which include gasoline direct- (CAFE) programme and Japan’s Top Runner energy injection and variable valve actuation technologies. They offer efficiency programme. China, Taiwan and South Korea up to 15% improved fuel efficiency relative to a comparable have also established mandatory fuel economy PFI engine while only requiring conventional automotive exhaust after-treatment. However, a sophisticated controller using cylinder pressure sensor and other control algorithms are required to manage the HCCI combustion process. 6 0.7 Euros to the Dollar throughout this paper 3

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standards while Austria has called for a voluntary US, Japan and China (although in Europe, new sales of industrial agreement to reduce fleet average fuel diesel cars surpassed gasoline cars in 2006). consumption for passenger cars. The California Air Advanced gasoline engines are expected to remain Resources Board (CARB) has issued regulations competitive in vehicle applications for the near future. If limiting the fleet average GHG emissions (CO2, CH4, technologies to improve gasoline engines can obtain a N2O and HFCs) from passenger cars. The Canadian better “cost to benefit” ratio in terms of CO2 reduction, it government also announced it will take measures to will be commercially attractive to introduce them into the reduce GHG emissions, shifting from its earlier new car fleet mix. Moreover, they are more technically voluntary Company Average Fuel Consumption (CAFC) mature than hydrogen and electric vehicles and can be programme to mandatory regulatory programmes. In deployed instantly using the existing infrastructure. the European Union, the Commission has proposed They can offer near-term solutions addressed to the new-car CO2 regulations, which require a fleet average climate issue, with affordable costs for customers. of 130g of CO2 per kilometre to be achieved by all cars Market potential may vary between countries depending registered in the EU, and a long-term target of 95g/km on availability, prices and the level of fuel duty between for the year 2020 [17]. petrol, diesel and alternative fuels. A few technical bottlenecks remain for some of the technologies Approximately 46.6 million new passenger cars were discussed such as the HCCI (CAI). Moreover, different sold worldwide in 2006, compared to 43.4 million in advanced technologies are being studied to a greater or 2005 [18, 19]. Apart from the ongoing economic crisis, lesser extent by different companies. Some of these not only emerging economies but also OECD countries technologies are mutually exclusive while others can be still show a strongly increasing car ownership rate [15]. additive (e.g. turbo-downsized GDI, GDI with VVT and Gasoline engines power the great majority of passenger VVL). Hybrid electric technology may also benefit from cars in the world, especially in countries such as the developments in advanced engines.

References and Further Information 1. EPA 2008, EPA Staff Technical Report: Cost and Effectiveness Estimates of Technologies Used to Reduce Light-duty Vehicle Carbon Dioxide Emissions, EPA420-R-08-008, United States Environment Protection Agency, March 2008. 2. EPA 2008, A Study of Potential Effectiveness of Carbon Dioxide Reducing Vehicle Technologies, Revised Final Report, EPA420- R-08-004a, United States Environment Protection Agency, June 2008. 3. IEA 2005, Making cars more efficient: Technology for Real Improvements on the Road, International Energy Agency and European Conference of Ministers of Transport Joint Report, 2005. 4. TNO 2006, Review and analysis of the reduction potential and costs of technological and other measures to reduce CO2-emissions from passenger cars, Contract nr. S12.408212, TNO/ IEEP/ LAT, October 2006. 5. Drake and Haworth 2007, Advanced gasoline engine development using optical diagnostics and numerical modelling, Proceedings of the Combustion Institute 31 (2007) 99-124. 6. Alkidas 2007, Combustion advancements in gasoline engines, Energy Conversion and Management 48 (2007) 2751-2761. [6] Mahle Powertrain 2007, Special Edition Mahle Powertrain, Customer magazine. 7. Lake et al. 2003, Turbocharging Concepts for Downsized DI Gasoline Engines. 8. Volkswagen brochure, TSI. A Miracle of Performance, http://www.volkswagen.co.nz/publish/vwasia/new_zealand/en/experience/technology/tsi_technology.html. 9. Renault http://www.renault.com/en/innovation/eco- technologies/documents_without_moderation/pdf%20env%20gb/integrale%20env%20gb.pdf. 10. BMW’s Valvetronic http://www.bmw.com/com/en/insights/technology/technology_guide/articles/mm_valvetronic.html. 11. Honda’s VTEChttp://world.honda.com/news/2006/4060925VTEC/. 12. Nissan’s VVEL http://www.nissan-global.com/EN/TECHNOLOGY/INTRODUCTION/DETAILS/VVEL/index.html 13. EC2002, Variable Compression Ratio Technology for CO2 Reduction of Gasoline Engines in Passenger Cars, European Commission Community Research. http://ec.europa.eu/research/growth/gcc/projects/provcr.html. http://ec.europa.eu/research/conferences/2002/pdf/presspacks/1-1-vcr_en.pdf. 14. Carbon Trust 2003, Low Cost Solution for Gasoline Engine Controlled Auto Ignition, Project reference number 2003-5-22. 15. General Motor http://www.gm.com/experience/fuel_economy/news/2007/adv_engines/new-combustion-technology-082707.jsp 16. ETP 2008, Energy Technology Perspectives 2008, International Energy Agency. 17. ICCT 2007, Passenger Vehicle Greenhouse Gas and Fuel Economy Standards: A Global Update, International Council on Clean Transportation (ICCT), www.theicct.org. 18. ACEA 2008, European Automotive Industry Report 07/08, 2008. 19. ACEA 2006, European Automotive Industry Report 2006, 2006. 20. Kollamthodi, S. et al., Transport technologies marginal abatement cost curve model - technology and efficiency measures, AEA Technology, 2008. 21. DOE 2008, FY 2008 Progress Report for Advanced Combustion Engine Technologies, Energy Efficiency and Renewable Energy, Office of Vehicle Technologies, U.S. Department of Energy, December 2008. 22. Ford EcoBoost, gasoline engines with turbocharging and direct injection technology http://www.ford.com/about-ford/news- announcements/press-releases/press-releases-detail/pr-affordable-technology-for-today-27833# 23. General Motor’s advanced engine technologies (VVT, direct injection, cylinder deactivation, direct injection with turbocharging) http://www.gm.com/corporate/responsibility/reports/08/400_products/4-2-1.jsp 24. Volkswagen’s TSI engines (gasoline direct injection with turbocharging and supercharging) http://www.volkswagen.co.nz/publish/vwasia/new_zealand/en/experience/technology/tsi_technology.html

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Table 2 – Summary Table: Key Data and Figures for Baseline and Advanced Gasoline Vehicles

Baseline Vehicles (Source [20]) Technical Performance Small Cars Medium Cars Large Cars Energy Input Gasoline Energy Output Kilometres Base Energy Consumption (l/km) 0.062 0.072 0.111 Technical Lifetime, yrs 12 12 12 Environmental Impact CO2 and other GHG emissions, g/km 143.5 166.7 255.0 Costs Capital Cost, overnight, Euro/unit 10,279 16,643 25,505 O&M cost (fixed and variable), Euro/km 0.03 0.04 0.05 Economic Lifetime, yrs 12 12 12 Advanced Vehicles (Source [20]) Technical Performance Small Cars Medium Cars Large Cars Energy Input Gasoline Energy Output Kilometres Base Energy Consumption (l/km) 0.055 0.064 0.097 Technical Lifetime, yrs 12 12 12 Environmental Impact CO2 and other GHG emissions, g/km 126.3 146.7 224.4 Costs Additional Capital Cost, overnight, Euro/unit 231 – 401 308 – 462 130 – 524 O&M cost (fixed and variable), Euro/km 0.03 0.04 0.05 Economic Lifetime, yrs 12 12 12

Table 3 – CO2 Emission Reductions for Advanced Gasoline Technologies Drake IEA IEA CO reduction (%) TNO/IEEP/LAT and 2 EPA 2008 [1] 2005 2008 2006 [4] Haworth [2] [3] 2007 [5] Small Large Small Medium Large Reduced engine friction losses 1-3 1-3 2-4 3 4 5 DI / homogeneous charge (stoichiometric) 1-2 1-2 3 3 3 3-5 8-12 12-15 3-5 9-12 10-14 10 10 10 (WG); 20 DI/Stratified charge (lean burn/complex strategies) (SG) Mild downsizing with turbocharging 2-4 Medium downsizing with turbocharging 6-9 6-9 2-3 8.5 10 10 Strong downsizing with turbocharging 12 12 12 Variable Valve Timing 2-3 1-4 1.5-2.5 6-8 3 3 3 Variable valve control 4-5 3-6 5-7 7 7 7 Cylinder deactivation 6 6-8 Controlled auto-ignition (CAI) /Gasoline HCCI 11-14 11-14 20 dual-mode

Table 4 – Incremental Costs of Advanced Gasoline Technologies

EPA 2008 [Euro] [1] TNO/IEEP/LAT 2006 [Euro] [2] Small Large Small Medium Large Reduced engine friction losses 0-58 0-88 40 50 60 DI / homogeneous charge (stoichiometric) 85-294 143-368 125 150 175 DI / Stratified charge (lean burn / complex strategies) 610-819 668-893 320 400 480 Mild downsizing with turbocharging Medium downsizing with turbocharging 225 300 375 Strong downsizing with turbocharging 390 450 510 Variable Valve Timing 41-62 41-146 100 150 200 Variable valve control 118-419 172-883 300 350 400 Cylinder deactivation 142 Controlled auto-ignition (CAI) /Gasoline HCCI dual-mode 270-478 416-641

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